That was April 2011, six years after the release of their first album. Brothers Chris and Oliver Wood each had enjoyed noteworthy careers before they’d come together: Guitarist Oliver’s projects had included the blues-rock jam band King Johnson, and bassist Chris had broken new ground with the unconventional jazz trio Medeski Martin & Wood. Together they’d become known for a delicate folk/Americana sound, but that was changing. They’d added a percussionist to the mix and were busily exploring the new territory that opened up.

On Thursday evening, the Wood Brothers return for a show at the Alabama Music Box, and the group is positively bristling with new music. (Carsie Blanton opens the 18-and-up show, which has an advertised start time of 7 p.m. Tickets are $15, available through www.alabammusicbox.net.)

So far this year, the trio has released two live sets, “Sky High” and “Nail & Tooth.” Each is short, but together they clearly show a band that is feeling its strength. There’s more electric guitar in the mix now; more shouting, ecstatic gospel influence; more rock. They can still be quiet, but when they get rowdy they can really make listeners stand up and take notice.

Things are “rolling along pretty good,” Oliver Wood said in a recent interview. “We’re happy to have these two live albums under our belts now.” They’re definitely playing that material on their current tour, he said, but “at the same time we’re already thinking about our new studio album that we’re going to record this year. We’re working on a lot of new music and playing a lot of new music too.”

Some bands prefer to keep new material under wraps until it comes out on an album. Wood said he and his brother find it essential to field-test new tunes.

“The finishing touches on songs often come in that process of playing live, when you can see what’s working and what’s not working, and you can kind of tweak them as you go,” he said. “I always feel better about recording something in the studio when it’s sort of been tried and tested a little bit.”

Take this much for granted: They’re not giving up their newfound muscle anytime soon.

“One thing about having drums is, we can get over in places that are not listening rooms, so we have more flexibility,” Wood said. “But I think we still love, our favorite places to play are where the audiences are somewhat captive and really focusing on the music rather than the bar or socializing or whatever.”

Wood said the group strikes a balance between the honoring the roots influences it loves, and doing its own thing. And that has helped it build a diverse audience, from jam-festival crowds to NPR listeners. They’re rooted in Americana, blues, gospel and rock, but committed to doing their own thing, he said.

“We try real hard not to be just a regular old rock and roll trio,” Wood said. “Our music is somewhat eclectic but we definitely think of it as roots-inspired music. And we don’t feel limited about how we approach that.”